Closed robots closed 4 years ago
Hi robots, Thanks for the advice, but I cannot recommend to follow your advice. The RSSI without tag, with exactly the components of the BOM, should be more than 10V - all of the ChameleonMini RevG sold in the webshop of Kasper&Oswald have to pass this test! It seems that you have made some other mistake during manufacture. I have spent about a week for fine-tuning the antenna matching both for emulation and reader operation of Rev.G, before we had several thousand devices produced after the kickstarter project... and changing the value of a single (or even 2) capacitors affected all capabilities (sniffing, reading, emulating, ...) it was a tidious try-and-improve approach and I think we have found a good compromise for the tuning.... anyway, 2500mV is definitely not enough, there is s.th. wring with your device.
Well, its been 2years since i made the board. I dont remember what parts were ordered, but it could be problem on my side :-) I will replace all RF frontend parts just to be sure.
What is the capacitance value of C29 C30
these capacitors are not populated in BOM
See pictures c29 and c30 in the wiki https://github.com/emsec/ChameleonMini/wiki
Hi, for all of you guys who made Chameleon Mini on their own here is little advice:
Capacitors C29 and C30 should be 47pF.
This tunes the mismatch between transmitter and antenna. It increases reader distance from -1 to about 2-3cm. RSSI without tag changes from 500-600 to ~2500mV.
More about this here: https://my.eng.utah.edu/~mlewis/ref/NFC/AN1445.pdf